drivers/rtc/rtc-em3027.c

0001 // SPDX-License-Identifier: GPL-2.0-only
0002 /*
0003  * An rtc/i2c driver for the EM Microelectronic EM3027
0004  * Copyright 2011 CompuLab, Ltd.
0005  *
0006  * Author: Mike Rapoport <mike@compulab.co.il>
0007  *
0008  * Based on rtc-ds1672.c by Alessandro Zummo <a.zummo@towertech.it>
0009  */
0010
0011 #include <linux/i2c.h>
0012 #include <linux/rtc.h>
0013 #include <linux/bcd.h>
0014 #include <linux/module.h>
0015 #include <linux/of.h>
0016
0017 /* Registers */
0018 #define EM3027_REG_ON_OFF_CTRL  0x00
0019 #define EM3027_REG_IRQ_CTRL 0x01
0020 #define EM3027_REG_IRQ_FLAGS    0x02
0021 #define EM3027_REG_STATUS   0x03
0022 #define EM3027_REG_RST_CTRL 0x04
0023
0024 #define EM3027_REG_WATCH_SEC    0x08
0025 #define EM3027_REG_WATCH_MIN    0x09
0026 #define EM3027_REG_WATCH_HOUR   0x0a
0027 #define EM3027_REG_WATCH_DATE   0x0b
0028 #define EM3027_REG_WATCH_DAY    0x0c
0029 #define EM3027_REG_WATCH_MON    0x0d
0030 #define EM3027_REG_WATCH_YEAR   0x0e
0031
0032 #define EM3027_REG_ALARM_SEC    0x10
0033 #define EM3027_REG_ALARM_MIN    0x11
0034 #define EM3027_REG_ALARM_HOUR   0x12
0035 #define EM3027_REG_ALARM_DATE   0x13
0036 #define EM3027_REG_ALARM_DAY    0x14
0037 #define EM3027_REG_ALARM_MON    0x15
0038 #define EM3027_REG_ALARM_YEAR   0x16
0039
0040 static struct i2c_driver em3027_driver;
0041
0042 static int em3027_get_time(struct device *dev, struct rtc_time *tm)
0043 {
0044     struct i2c_client *client = to_i2c_client(dev);
0045
0046     unsigned char addr = EM3027_REG_WATCH_SEC;
0047     unsigned char buf[7];
0048
0049     struct i2c_msg msgs[] = {
0050         {/* setup read addr */
0051             .addr = client->addr,
0052             .len = 1,
0053             .buf = &addr
0054         },
0055         {/* read time/date */
0056             .addr = client->addr,
0057             .flags = I2C_M_RD,
0058             .len = 7,
0059             .buf = buf
0060         },
0061     };
0062
0063     /* read time/date registers */
0064     if ((i2c_transfer(client->adapter, &msgs[0], 2)) != 2) {
0065         dev_err(&client->dev, "%s: read error\n", __func__);
0066         return -EIO;
0067     }
0068
0069     tm->tm_sec  = bcd2bin(buf[0]);
0070     tm->tm_min  = bcd2bin(buf[1]);
0071     tm->tm_hour = bcd2bin(buf[2]);
0072     tm->tm_mday = bcd2bin(buf[3]);
0073     tm->tm_wday = bcd2bin(buf[4]);
0074     tm->tm_mon  = bcd2bin(buf[5]) - 1;
0075     tm->tm_year = bcd2bin(buf[6]) + 100;
0076
0077     return 0;
0078 }
0079
0080 static int em3027_set_time(struct device *dev, struct rtc_time *tm)
0081 {
0082     struct i2c_client *client = to_i2c_client(dev);
0083     unsigned char buf[8];
0084
0085     struct i2c_msg msg = {
0086         .addr = client->addr,
0087         .len = 8,
0088         .buf = buf, /* write time/date */
0089     };
0090
0091     buf[0] = EM3027_REG_WATCH_SEC;
0092     buf[1] = bin2bcd(tm->tm_sec);
0093     buf[2] = bin2bcd(tm->tm_min);
0094     buf[3] = bin2bcd(tm->tm_hour);
0095     buf[4] = bin2bcd(tm->tm_mday);
0096     buf[5] = bin2bcd(tm->tm_wday);
0097     buf[6] = bin2bcd(tm->tm_mon + 1);
0098     buf[7] = bin2bcd(tm->tm_year % 100);
0099
0100     /* write time/date registers */
0101     if ((i2c_transfer(client->adapter, &msg, 1)) != 1) {
0102         dev_err(&client->dev, "%s: write error\n", __func__);
0103         return -EIO;
0104     }
0105
0106     return 0;
0107 }
0108
0109 static const struct rtc_class_ops em3027_rtc_ops = {
0110     .read_time = em3027_get_time,
0111     .set_time = em3027_set_time,
0112 };
0113
0114 static int em3027_probe(struct i2c_client *client)
0115 {
0116     struct rtc_device *rtc;
0117
0118     if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C))
0119         return -ENODEV;
0120
0121     rtc = devm_rtc_device_register(&client->dev, em3027_driver.driver.name,
0122                   &em3027_rtc_ops, THIS_MODULE);
0123     if (IS_ERR(rtc))
0124         return PTR_ERR(rtc);
0125
0126     i2c_set_clientdata(client, rtc);
0127
0128     return 0;
0129 }
0130
0131 static const struct i2c_device_id em3027_id[] = {
0132     { "em3027", 0 },
0133     { }
0134 };
0135 MODULE_DEVICE_TABLE(i2c, em3027_id);
0136
0137 #ifdef CONFIG_OF
0138 static const struct of_device_id em3027_of_match[] = {
0139     { .compatible = "emmicro,em3027", },
0140     {}
0141 };
0142 MODULE_DEVICE_TABLE(of, em3027_of_match);
0143 #endif
0144
0145 static struct i2c_driver em3027_driver = {
0146     .driver = {
0147            .name = "rtc-em3027",
0148            .of_match_table = of_match_ptr(em3027_of_match),
0149     },
0150     .probe_new = em3027_probe,
0151     .id_table = em3027_id,
0152 };
0153
0154 module_i2c_driver(em3027_driver);
0155
0156 MODULE_AUTHOR("Mike Rapoport <mike@compulab.co.il>");
0157 MODULE_DESCRIPTION("EM Microelectronic EM3027 RTC driver");
0158 MODULE_LICENSE("GPL");